High-Quality Graphene p−n Junctions via Resist-free Fabrication and Solution-Based Noncovalent Functionalization

Abstract

An essential issue in graphene nanoelectronics is to engineer the carrier type and density and still preserve the unique band structure of graphene. We report the realization of high-quality graphene p-n junctions by noncovalent chemical functionalization. A generic scheme for the graphene p-n junction fabrication is established by combining the resist-free approach and spatially selective chemical modification process. The effectiveness of the chemical functionalization is systematically confirmed by surface topography and potential measurements, spatially resolved Raman spectroscopic imaging, and transport/magnetotransport measurements. The transport characteristics of graphene p-n junctions are presented with observations of high carrier mobilities, Fermi energy difference, and distinct quantum Hall plateaus. The chemical functionalization of graphene p-n junctions demonstrated in this study is believed to be a feasible scheme for modulating the doping level in graphene for future graphene-based nanoelectronics.

Low Carrier Density Epitaxial Graphene Devices On SiC

“…We conclude with results of processing sample S5 with Polymethyl methacrylate (PMMA), a common electron‐beam photoresist. The possible applications of this type of polymer would be for stabilizing the carrier concentration, photochemical gating, or to create p‐n junctions . Figure a shows transport characteristics of device S5D2 before applying PMMA, with n‐type carrier density of 7.4 × 10 11 cm −2 .…”

Patterned graphene ablation and two-photon functionalization by picosecond laser pulses in ambient conditions

“…The traditional silicon microelectronic technology is not fit for 2D carbon nanomaterials, whose structural basis is an atomically thin layer, and with properties closer to molecular ones rather than to solid state. 4 Besides, optical properties of graphene lattice are still not fully harnessed and have large applicability perspectives in optoelectronic devices and sensors. Non-linear interaction between photons and carbon bonds not only provides the possibility to design unique photonic devices but also opens the paths for laser-based graphene processing.…”

Ballistic electron propagation through periodic few-layer graphene nanostructures

“…This assumption is not always accurate, especially at gate-induced potential barrier steps in graphene, where finite p-n junction widths are required to reproduce experimental results on ballistic propagation [41]. However, recent technological advances in fabricating graphene junctions aim to produce high-quality devices with potential barrier interfaces that tend to resemble as close as possible atomic interfaces [42][43][44]. On the other hand, atomic sharp interfaces occur between graphene and semiconductors such as InSe [45], Si [46] or h-BN [47].…”